This invention relates to a method for manufacturing vehicle wheel rims. More specifically, the invention relates to a method wherein a roll formed wheel rim of a given width, and profile, is axially stretched to produce a finished wheel rim having an axial width greater than the original.
U.S. Pat. No. 4,185,370 discloses a prior art method of making roll formed wheel rims. The method comprises a plurality of forming steps sequentially applied to a hoop or band of material. The first forming operation comprises preforming the rim flange areas by flaring the lateral edges of the band or hoop. Once the band is flared, a well section, having a diameter less than the diameter of the band, is formed by a first roll forming operation. A second roll forming operation is then carried out to flatten the well section, further define the rim flanges and to provide safety hump areas. A final roll forming operation followed by an expander operation gives the rim its final dimensions. Wheel rims produced by this method have a relatively uniform material thickness throughout their axial cross-section equal to that required in the bead seat and flange areas. We have found that such a material thickness is not necessarily required in the well and inboard leg area of the rim.